How to Manage Pests

UC Pest Management Guidelines

Alfalfa

Crop
Rotation

Avoid planting alfalfa directly into a
field from which an alfalfa crop was recently removed. Rotation to a nonhost
crop can significantly reduce pest populations in the field. The table below
provides information on nonhost crops that suppress alfalfa-associated nematode
and pathogen populations. Also included are a list of crops in which herbicides
that are not registered for use in alfalfa can be used to manage weeds.

If your field is infested with stem
nematode or pathogens listed in the key below, consider choosing a nonhost crop
from the table. Although 3- to 4-year nonhost crop rotations are ideal, they
are not commonly practiced. A rotation of lesser duration is still beneficial
but to a lesser degree.

For winter weed control, choose a
wheat or oat crop rotation and an herbicide treatment. Manage summer weeds by
growing a corn rotation and using selective herbicides and cultivations. For
fall plantings, rotate to another crop to manage established weeds such as
nutsedge, bermudagrass, or burclover because they are not effectively
controlled with herbicides used in conventional alfalfa.

Volunteer alfalfa around the field
edges of a rotation crop may perpetuate nematode populations. If your field has
a history of nematodes, be sure to remove all volunteer alfalfa.

A
minimum of 1 year (preferably longer) in crops such as small grains, wheat,
oats, winter forage grasses that allow the use of selective herbicides that are not registered in alfalfa.

Summer weeds

A minimum of 1 year (preferably longer) in crops
such as small grains, beans, cotton, corn, sorghum, summer forage grasses
that allow the use of selective herbicides that are not registered in alfalfa.

At least 2 years with cotton or other nonhost crops
such as small grains, beans, corn, sorghum, or forage grasses. Avoid
rotations with crops such as tomatoes, onions, and carrots that also serve as
a host for this weed.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.